Engineering Pharmaceutical Nanoparticles

Cory BerklandAssistant Professor Department of Pharmaceutical Chemistry

Assistant Professor Department of Chemical and Petroleum EngineeringThe University of Kansas

2

Acknowledgements

Postdocs:David Shi, Nancy Zhang, Laura Peek, Min Huang

Graduate Students:Matt Arnold, Abdul Baoum, Qun Wang, Milind Singh, Mark Bailey, Carl Plumley

Undergraduates:Casey Morris, Tina Coop, Ryan Ellis

Funding:NIH, American Heart Association, Cystic Fibrosis Foundation, PhRMAFoundation, Juvenile Diabetes Research Foundation, HBC, KMCRI

Special thanks:The Microscopy Lab at KU, Prof. Russ Middaugh and lab members.

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Nano perspective….

SARS virus

human T-lymphotropic virus

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Nanometer size particles are small enough to enter cells.

Particle size >200 nm enables intracellular delivery.

www.genovis.com

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Particle engineering is critical for pharmaceutical applications.

– Dissolution rateControl size

– Pulmonary delivery~3 microns

– Nasal delivery~5-20 microns

– Embolism~10-20 microns

– Avoid RES>150 nm

– Target “leaky” vessels<250 nm

– Endocytosis~200 nm

Control particle…– Size and distribution– Morphology– Surface roughness

Dispersibility– Surface chemistry

PassivateActivate

– Consistency/quality control– Product lifecycle management

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Current practices are process intensive and harsh for fragile API.

Shear PolymorphismHeat Loss of activity

Contact Materials Contamination

www.retsch.de

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For example, the bioavailability of poorly soluble drugs can be enhanced.

Spironalactone is a synthetic 17-lactone steroid. Nanoparticle suspensions of this drug dramatically enhance the drug dissolution.

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For example, tumor accumulation via “enhanced permeability and retention.”

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For example, tumor accumulation via “enhanced permeability and retention.”

Nishiyama (2006)

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Question:How do you create particles?

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A multitude of methods may be used to engineer particles.

Top Down– Milling/grinding

Bottom up– Crystallization– Spray drying– Ionic complexation– Self assembly

www.buchi.com and LaVan, et al. (2002)

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Outline of particle engineering technologies covered.

Milling/Spraying TechnologyCrystallization Technology Supercritical FluidsPolymer NanoparticlesMolecular Technology/PolyplexesBlock copolymers – micellesLiposomes/PolymersomesPolymer/Drug conjugatesBerkland Lab

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Milling/SprayingTechnology

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Wet milling provides a method to reduce the particle size of poorly soluble API.

www.elan.com and Merisko-Liversidge, et al. (2003)

Intensive process Particle recovery required

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Air jet milling reduces particle size to 1-30 microns or smaller.

Air jet milling– Particle-particle collisions – No heat or moving parts

>30 kg/hr production Low power consumption

www.microntech.com and www.sturtevantinc.com

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Spray drying can be utilized for engineering particle size/morphology.

Size control– Somewhat

Density controlDispersibilityStability

Small molecule API

Large molecule API

Particle diameter ~3 micronsleads to deep lung deposition

daero = dp (ρ/ρref)0.5

www.nektar.com

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Crystallization Technology

For background see Rabinow (2004)

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Crystals can be designed to be small and friable for nanosizing.

www.baxterbiopharmsolutions.com

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C3 technology uses ultrasound to control crystal formation.

Control nucleation Enhance yield Reduce agglomeration Fewer imperfections Increase reproducibility Eliminate seeding?No sonicator contactCrystal formation at higher T

www.accentus.com

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Nucleation induced by sonication increases crystal homogeneity and yield.

Sonication techniques applied to emulsion crystalization processes provide control over nucleation, crystal size, and quality.

www.glaxosmithkline.com,

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Post-crystallization processing decreases particle size (submicron).

Rabinow (2004)

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High pressure homogenization is another technique.

24 Rabinow (2004)

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Supercritical Fluids (SCF)

For a review, see Yeo, et al. (2005)

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Ultrasonic nozzle, SCF anti-solvent (SAS) process offers decent scalability.

Maximum Capacity: 0.5 kg/8 h www.crititech.com

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SCFs provide high diffusion coefficients for rapid/complete solvent extraction.

Reduced particle size by SASNarrow size distributionsSmall molecules, proteins and peptidesMinimal residual solvent

www.crititech.com

Before processing After processing

Expensive?

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Spray-freezing into SCF provides a novel means to create protein particles.

Williams, et al. (2004), Leach, et al. (2005) and www.alkermes.com

Spray-freezing into SCF produces micron or sub-micron protein particles. Particles can also be homogenized in SCF (cryo-milled) to further reduce particle size.

Sieved

SCF processed

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Polymer Nanoparticles

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Baxter’s PROMAXX microspheres have decent size control for API delivery.

Sustained or immediate releaseSized for delivery– Deep lung

Fabrication– Aqueous– Polyethylene glycol– Insulin crystals– Lower T

Stable (dry)www.baxter.com

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Pure protein particles produced by freeze-drying with PEG, removing PEG.

Freeze-drying albumin with PEG particles.PEG:Albumin 1 0.1 9

9

1

0.1

0

Morita, et al. (2000)

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Bulk “gel” materials can be made from crosslinked nanoparticles (oral delivery).

www.accesspharma.com

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Molecular Technology/Polyplexes

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Dendrimers are gaining interest for delivering drugs and sensing.

Easy formulation?Size control (Mw)Complex or intercolate drugs– Low drug loading

Marketed products

www.dnanotech.com

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Polyelectrolyte complexes can be formulated to contain API.

Long used for gene delivery, PEI-DNARecently, for enhanced transport across BBB

Ogawa (2005), Li (2004) and Vinogradov (2004)

Drug is usually mixed with polymer 1 (binding) and polymer 2 (opposite charge) is dripped in with mixing to form nanogels via ionic complexation.

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LBL-Technology® can form capsules by using uniform particle templates.

Ger. Offen. (2004) and Peyratout (2004)

Ordered shellsDense shells4-24+ layers (8-50 nm) API encapsulation– Entrapped in layer– Partitioned into core

Surface active

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LBL controls drug locale, particle morphology or coating of drug crystals.

Ger. Offen. (2004) and Peyratout (2004)

API crystals can be selectively coated

Drug localized to specific shell layer or core.

Morphology control may reduce aggregation

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Block copolymers - micelles

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Block copolymers self assemble in solution to form micelles.

Nishiyama (2006)

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Block copolymers entrap poorly soluble drugs in the core of micelles.

Improved solubility of poorly soluble drug

Amprenavair – HIV protease inhibitor Formulated with Vitamin E TGPS to improve pharmacological properties (solubility, permeability, etc.

Micelle Labs, Inc.

~40 nm diameter

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Micelles accumulate in tumors through “enhanced permeability and retention.”

Vicent (2004), Nishiyama (2006)

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Liposomes/Polymersomes

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Liposomes like the STEALTH® liposome may target delivery.

PEG coating– Reduces MPS uptake – Increase residence– Plasma stability

Lipid shell/water core– Decent drug load– Low permeability

~100 nm– Increase residence– Extravasation

FRAGILE!Been around and minimal products

www.alza.com

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Polymersomes offer an attractive alternative to liposomal formulations.

Geng (2005), Ahmed (2004) and Hammer (2001)

PCL-PEG (biodeg.)Morphology controlCross-linked but flexibleWorms circulate 1 week!

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Combination chemotherapy reduced tumor size in vivo.

Polymersomes loaded with paclitaxel and doxorubicinimprove the performance of these drugs by accumulating in the tumor after IV injection and controllably releasing these two drugs.

Ahmed (2006)

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Polymer/Drug conjugates

47 Vicent (2004), Nishiyama (2006)

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BerklandLab Dry powder aerosols

– Cystic Fibrosis Foundation, PhRMA FoundationProtein stabilization in nanoparticles

– American Heart AssociationNanoparticle targeting

– Juvenile Diabetes Research FoundationIntracellular drug delivery

– NIH, HBC, KMCRIImplantable controlled release films

– Juvenile Diabetes Research Foundation

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Particle engineering is critical for pharmaceutical applications.

- Dissolution rateControl size

- Pulmonary delivery~3 microns

- Nasal delivery~5-15 microns

- Embolism~10-20 microns

- Avoid RES>150 nm

- Target “leaky”vessels

<250 nm- Endocytosis

<200 nm

Control particle…- Size and distribution- Morphology- Surface roughness

DispersibilityFlowability

- Surface chemistryPassivateActivate

- Consistency/quality control- Product lifecycle management

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Micro- and nanoparticles possess advantages for discrete applications.

Microparticles- Control release rate

Reservoir or matrix type devices

- Protect drugsCo-encapsulation of excipients

- Passive localizationDepots - ~10-100 µmNasal - ~10 µmLung - ~2-10 µm

- Immune responseVaccine adjuvant ~1-5 µm

Nanoparticles- Enhance dissolution

Poorly water soluble drugs

- Extend circulation>10 nm retained in blood

- Passive targetingEnhanced permeability and retention (tumors) ~100 nm

- Enter cellsIntracellular drug delivery <200 nm

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Exercising control over micro- or nanoparticle structure.

Microparticles Nanoparticles

~100 µm aqueous core/ PLGA shell (rhodamine-labeled albumin)

~50 µm PLGA core/ polyanhydride shell (Balaji Narasimhan)

~200 nm poly(vinyl-formamide) pH-sensitive nanocapsules

~100 nm silica nanoparticles

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Ciprofloxacin nanoparticles associated with PLGA microparticle carriers.

Monodisperse low-density PLGA microparticles for deep-lung delivery of poorly soluble antibiotics.

Porous and irregular structure improves aerosol performance.

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Exercising control over micro- andnanoparticle structure.

Nanoparticles as building blocks pH-sensitive nanoparticle clusters

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Coating nanoparticles with PNVF allowed dispersion in response to pH.

Nanoparticle clusters disperse over a few hours at pH 5.

pH 7

pH 8

pH 6

pH 5pH 4

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Controlled agglomeration of nanoparticles for inhaled dry powders.

StirringSyringe pump

---+

+-+

+ +-

- --++-++ +-

- --++-++ +-

Freeze Dried Powder

- --++ -++

+-- --++-++ +-

Filter

---+

+-+

++-

- --++ -++

+-- --++-++ +-

---+

+-+

++-

Nanosuspension Assembly

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Self assembled PLGA nanoparticles form a low density cluster.

+

Rhodamine-labeled (-) PLGA particles

FITC-labeled (+) PLGA particles

Scale bar = 10 µm

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PLGA nanoparticle clusters possess attractive aerodynamic properties.

γρρ 5.0)/( refn

aero

dD =

0 5 10 15 20 25 300.0

0.5

1.0

1.5

2.0

2.5BA

A: Aerodynamic diameterB: Geometric Diameter

Vol

ume

%

Diameter (micrometers)

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pH sensitive nanocapsules may selectively deliver drugs intracellularly.

0 20 40 60 80 100 120 140 16020

30

40

50

60

70

80

90

100pH=5.6pH=7.4

% T

rans

mitt

ance

Time (min)

~200 nm poly(vinyl-formamide) pH-sensitive nanocapsules

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Conclusions

Particle technology is developing rapidly!May need to match method to particular API formulation.A portfolio of approaches improves chances of success (e.g.Dow’s BioAqueous).

Conners, et al. (2004)

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References

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